Help! Am making some grapefruit marmalade for a friend and I can't seem to get it to set. It was at 220 for about 7-8 minutes, and all the zest has come to the top and all of the top was getting a nice gloopy set. But all of the liquid underneath was still runny! I had the pectin bag in, and kept giving it a good stir, but not joy. I jarred it up last night but still runny now. I've poured it back into the jam pan but does anyone have any ideas/ tips? Made it a couple of years ago no probs!